For example, look at the sales of the biggest games for the 2nd Half of 2011 Vs the 2nd Half of 2010 (for the PS3 and 360). 



2010

2011

Clearly, individual game sales were actually better for 2011 - the year which was arguably the most packed year for the PS360. Using almost any methods of comparison, the games released in 2011 seemed to be better off than the games released in 2010. And what's even moer impressive is that most of these installments broke records their respective series. For example, these games were the fastest selling games of their series in 2011: Modern Warfare 3, Battlefield 3, Fifa Soccer 12, Skyrim, Arkham City, Gears of War 3, Uncharted 3, Saints Row 3, etc. And that's just from the above chart. There were also more smaller games that broke series records (eg. Dark Souls)

Also, 2011 also hosted a lot of successful new IPs like Dead Island and Rage. And lastly, even the smaller games did better in 2011. 2011 had more one-million sellers than 2010. Very few games from 2011 saw lower sales than their predecessors. And for the ones that did, they were usually considered inferior to their predecessors and/or were only lower by a small bit.

So, when people say "Call of Duty is eating into the sales of smaller Games", they're actually wrong. Call of Duty and other Big Games are helping the entire market. I personally don't know why or how this happens. It would seem logical that with more big games in one time period, more games will suffer. One would think that consumers have a finite amount of money and therefore there's only room for a certain amount of big games. But there's clearly a correlation here that suggests otherwise. Software sales have been increasing every year for the PS360. Apparantly, as long as new games are released, consumers will flock to them

I personally thought that a few games from last year would flop simply because the year was so crowded, but that didn't happen. But to my surprise, most of the games I feared for sold extremely well. I guess a crowded season helps other games by encouraging people to go to stores, therefore increasing the chances of other games being bought? Or maybe a crowded season increases the install base of consoles, therefore helping other games sales? I'm not sure the cause of this, but I think the correlation is clear.

- - Also, you can look at the games for past years too. 2009, 2008, 2007, etc. 2011 is the year with the biggest selling games. And 2011 seems to be the most crowded year.

- - I haven't looked at what happens in other parts of the year, but I assume it would be similar.

Thoughts? Is this phenomenon merely the result of an ever increasing installbase? Or is having more games released in a certain time period actually benefit every game? 

Well those games did release in the holiday season which more people would be willing to spend money anyway. And 2nd all those games you listed are sequels in multimillion selling series. They have their fans who would buy those games no matter what else. IMHO, i think to really get a good look at this you would have to check for games that arent nearly as popular as those. For instance Rayman origins dropped the same day as AC Revelations and well you could see the results

It's not possible to know if Rayman was affected by Assassin's Creed. Rayman Origins wasn't apart of a series, so we can't look at predecessors to see if it dropped. If there was a noticeable drop, then we could blame it on the more crowded time period. That's why I included the sequels. Because we could look back at predecessors and make comparisons with predecessors. It's really impossible to know if a reboot or new IP was affected because we have nothing to compare those too. 

In 2011, nearly every sequel released (big and small games) outperformed it's predecessor. And the ones that didn't were only less by a small bit. (I think Resistance 3 was the only game that didn't follow this rule). I think this suggests that packed seasons aren't as harmful as we thought they were, at least. One might argue that packed seasons are actually beneficial.

the original Rayman sold about 3mil on PS1 alone, it is part of the Rayman series and has dropped alot since then, but you are right we have no proof it was affected, I just dont think releasing on the same day as AC helped it. As I said before those sequels werent affected because they are sequels people will buy them regardless of how crowded the release season is. 

there's no way to disprove/prove it. if your broke and only have enough money for a few games,then in that case the sales will suffer for certain games. If your rich and can buy any game that you want,then it does'nt matter if it's a packed release schedule. to me if a smaller game is delayed to the first part of the year,then that makes sense. You see it all the time. There's just to many factors,to know if it's a myth are fact.

Deductive reasoning alone disproves such a argument. While this time frame may be more conducive to game sales. It is not conducive to better sales for all. Which is why new games are released year round, and why big games will come out in off peak months. If a game wouldn't qualify to be in the top ten of sales, or it would be genre overkill. Then there is a strong financial incentive to not release in this period.

To put it another way if a game looks like it is going to be the twelfth most popular title of the season, and that may mean it will sell two million copies. It may be better for it to be the most popular game in a off season where it may sell three or four million copies. This is probably why we see a lot of games getting delayed every year to early in the next year. I think developers have run the numbers.

September through December may account for well over half the spending, but that means it can only bare so many games, and it can only reward so many big games.